Various mechanisms exist to allow computers and executing software applications to programmatically interact. For example, remote procedure call (“RPC”) protocols have long existed that allow a program on one computer to cause a program on another computer to be executed, and various object-oriented architectures such as CORBA (“Common Object Request Broker Architecture”) and DCOM (“Distributed Component Object Model”) provide similar capabilities. In addition, a variety of middleware programs have been implemented to connect separate applications (often of distinct types and from unrelated sources) to allow communication. For example, various EDI (“Electronic Data Interchange”) networks exist that provide standard mechanisms to allow a computer system of one user of the network to send data to a computer system of another user of the network.
The widespread popularity of the World Wide Web (“Web”) has provided additional opportunities for computers to inter-communicate. For example, much current Web use involves users interactively requesting Web pages from Web servers (e.g., via executing Web browser applications of the users) and receiving the requested information in response. In addition to such interactive user specification of requested information, there is also growing use of the Web to support the programmatic interaction of remote applications to exchange information via defined APIs (“application program interfaces”), such as via Web services.
Web services allow heterogeneous applications and computers to interact, and can be defined and implemented using a variety of underlying protocols and techniques. For example, some Web service implementations return data in XML (“extensible Markup Language”) format using HTTP (“HyperText Transport Protocol”) in response to a Web service invocation request specified as a URI (“Uniform Resource Identifier”), such as a URL (“Uniform Resource Locator”) that includes a specified operation and one or more query parameters. In other implementations, additional underlying protocols are used for various purposes, such as SOAP (“Simple Object Access Protocol”) for standard message exchange, WSDL (“Web Services Description Language”) for description of service invocations, and UDDI (“Universal Description, Discovery, and Integration service”) for discovery of available services.
Although computing systems and programs can thus interact in various ways, various limitations exist in the ways in which transactions and other interactions between different systems and programs can be established. For example, while some providers of Web services or other programmatic services are willing to make their services available for free and to anyone, the most useful and reliable services are often not freely available. Unfortunately, the mechanisms for providers of programmatic services and potential consumers of those services to agree upon payment and other terms for transactions can be time-consuming and difficult to use, as well as very restrictive for at least some of the parties. In particular, while some transactions result from manual negotiations between parties for services or information, such techniques are time-consuming and greatly restrict the volume of transactions that can occur, and also typically require the exchange of significant information about the parties, which can create an additional impediment to such transactions in some situations.
However, other than through such manual negotiations, agreements about the use of programmatic services that are not freely available are typically restricted to non-negotiated transactions in which one party defines conditions related to use of a service and/or information, with other potential parties limited to merely interactively and manually determining whether to accept those conditions (e.g., Internet access from a typical Internet Service Provider that is offered subject to various usage restrictions, or content that is offered subject to usage restrictions enforced by digital rights management software). In addition, while some techniques may allow a consumer to have at least limited control on how payments can occur on their behalf (e.g., by acquiring and using some form of e-cash with a specified value, which thus cannot be used by an unscrupulous third-party to cost the consumer more than that value), such techniques do not typically assist with the problems related to establishing transactions.
Thus, it would be beneficial to provide a solution that addresses these and other problems associated with the establishment of transactions related to programmatic services and/or that otherwise facilitates the interaction of computer systems and executing programs.